When I spread my peanut brittle out after it cooks I spread it on the back of a cookie sheet because I don't have a marble slab. I oiled the slab generously but it stuck like glue to the pan bottom. How do I keep it from sticking so I can stretch it out by hand to make it thinner?//

Welcome to D.C.!
Rather than use the bottom of a cookie sheet. Line the cookie sheet with buttered parchment paper or foil.

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